The present invention relates to an injection device of the type that receives a syringe, extends it, discharges its contents and then retracts it automatically. Devices of this general description are shown in WO 95/35126 and EP-A-0 516 473 and tend to employ a drive spring and some form of release mechanism that releases the syringe from the influence of the drive spring once its contents are supposed to have been discharged, to allow it to be retracted by a return spring.
In devices of this nature, it is desirable for the return spring to be sufficiently strong that it can retract the syringe quickly. However, it is then possible for the syringe to be retracted so forcefully that it escapes from those elements of the device that are supposed to hold it during the extension and retraction phases. The syringe may then be free to move around within the body of the device. This gives rise to a number of undesirable effect. Firstly, the syringe will rattle around in the body of the device, giving an impression of poor quality. Secondly, shaking the device, which may be encouraged in those patients of a certain disposition by the rattling noise made by the syringe, might break the syringe, allowing broken glass to escape. Moreover, if the device has a viewing window, through which the discharged syringe may be inspected, the syringe will no longer be correctly positioned relative to it.